The present invention relates to a process for preparing catalysts. More particularly, the present invention relates to a process for preparing catalysts in the form of beads, said beads comprising a catalytic agent and an alumina carrier. The present invention also relates to the catalysts so obtained.
Alumina is widely used as constituent of industrial catalysts for converting hydrocarbons and various organic compounds. For most of such applications, catalysts in the form of spheroidal particles or beads preferably are used. Among the main advantages of such beads are better wear and crushing strength and a more regular distribution in the reactors which reduces the pressure drop of the reactants passing through the reactors. Generally, the bead type catalysts comprising a catalytic agent and an alumina carrier, are prepared by impregnating alumina beads with a catalytic agent or with a compound which generates this catalytic agent by thermal or chemical treatment.
Several processes have already been proposed for preparing spheroidal alumina particles. One such process consists of dispersing an alumina hydrosol as droplets into a medium wherein gelation occurs, and thereafter, subjecting the beads which are obtained in the form of alumina hydrogel, to one or more aging treatments in order to obtain beads having a suitable mechanical resistance. According to another process, an alumina hydrosol is mixed with an ammonium salt and a synthetic polymer or a natural gum. The mixture is then dispersed into a water-immiscible medium and thereafter subjected to an aging treatment. Alumina beads prepared by some of these processes contain high amounts, even excessive sometimes, of impurities which are undesirable when these beads are used as catalysts or catalyst supports.
An object of the present invention is to provide a new and simple method for preparing catalysts in the form of spheroidal particles, consisting of one or more calalytic agents and an alumina carrier.
Another object of the present invention is to provide a new process for preparing catalyst particles whose catalytic activity is not inhibited by impurities.
A further object of the present invention is to provide a process to obtain catalyst beads having an improved mechanical strength.
Additional objects will become apparent from the following description of the invention herein disclosed.